Fuse



March 31, 1931- J. G. RIESMAN FUSE Filed Dec. 5, 1929 Patented Mar. 31, 1931 UNITED s'm'ras OF CAMBRIDGE, ROYAL ELECTRIC COMPANY Application, filed December 5, 1929. Serial No. 411,883.

This invention relates to fuses, more particularly of the plug type such as are commonly employed to protect house lighting cir- .cuits. Such fuses are made of various current capacities in accordance with the particular service which it is desired to protect and while it is customary to mark such fuses with the rated voltage and current, these marks of necessity are relatively inconspicuous and in many constructions may become more or less obliterated while the fuse is still serviceable. There is thus considerable danger of using a fuse of incorrect capacity, resulting in unnecessary burn outs and interruptions to service when the fuse capacity is too small and inadequate protection against excessive current when the fuse capacity is too large.

This invention, therefore, of marking of the fuses in a permanent manner which will indicate their respective capacities.

A further object is to accomplish this desirable result without in any way increasing the difficulty of determining by inspection blown from good fuses. v

A still further object is to accomplish this desirable result and at the same time to add to the attractive appearance of the fuses when they are exposed for sale.

According to this invention, therefore, the fuses of each different capacity are designed to present a distinctive color, the color being applied in a very cheap manner but so placed that it cannot be removed or or in handling.

In order also that the blown fuses may be distinguished readily from the serviceable fuses, it is desirable that the fusible element be enclosed in a chamber provided with a erased in service clear, transparent window of glass or material of equal transparency.

In accordance with this inventlon, therefore, the outer end or top of the fuse is composed of glass or similar material which provides such a window while a marginal portion about the window presents the desired color efl'eet, and for the sake of cheapness and security of sealing,

as well as for appearance, the margin and window are formed integral ward the window While the has the object distinctive andas a one piece transparent unit. Plug fuses are provided with metallic shells which screw into the standard plug sockets and this shell is in electrical connection with one end of the fusible element. l have found it possible to apply the color inwardly of this shell where it is protected by the shell, this color presenting a correspondingly tinted effect to the margin of the top when the fuse is viewed towindow portion is uncolored.

For a more complete understanding of this invention, reference may be had to the accompanying drawings in which Figure 1 is a top plan of the fuse.

Figure 2 is a side elevation partly broken away,

Figure 3 is a longitudinal central section through the transparent top showing one manner of applying the color.

As shown in these drawings, the fuse is of the general construction shown in the reissue patent of Baenziger No. 17,341, June 25, 1929, for Fuse plugs, although it is not limited to this construction. This fuse comprises a top member 1 formed of glass, or similar clear transparent material, and is provided with a tubular portion 2 having one end open as at 3 and the other end closed by a central transparent Window 4 surrounded by a margin 5 of increased thickness. The fuse also has a base member 6 of insulating material through the central end portion of which extends a button 7 of conducting material to which is secured 'one end of the fusible element 8. This fusible element extends in the form of a loop toward the window portion 4 of the top, and in position to be readily seen through this window portion is a portion 10 of reduced cross sectionas shown in Figure 1, which becomes ruptured upon excessive current flow, the condition of this portion whether whole or ruptured being clearly evident through the window 4.

The opposite end portion of the fusible element 8 is shown as extending backwardly toward the base 6 and within a sleeve 12 of paper or similar protective material, which prevents the hot metal when the fuse blows from contacting sufliciently with the glass'of the of the top top member to cause it to break or shatter. This end portion of the fusible element is .shown as extended rearwardly to the base member 6 and then out between the base member and the top member and along the outside of the portion 2 of the top member in a groove therein to the inner end of a conducting metal sleeve 15 to which it is secured as by means of solder at 16. This sleeve 15 is shown as provided with external threads which facilitate the screwing of the fuse into a correspondingly threaded standard socket. The tubular portion 2 may also, as shown, be provided with threads 17 mating the inner wall of the shell 15. The rear end of the sleeve 15 may be inturned as at )1/{8 to engage a portion of the base .6, thus tbs old the base and top assembled when the sleeve 15 is in position, the sleeve being prevented from turning after the parts are assembled by the securing of the fusible element 8 to the shell 15. The construction so far described is identical with the disclosure of the Baenziger reissue patent.

In accordance with the present invention a color effect is produced when the fuse is viewed from the top or toward the window, the color being preferably indicative of the capacity of the fuse. Thus, for example, all fuses of, say, 30 ampere rating such as are suitable for main lineprotection at the con trolling switch may be colored red, while all fuses of 15 ampere rating such as are suitable for protecting branch circuits may be colored green. If a main line fuse is to be replaced, therefore, it will be replaced by a red fuse, while if a branch line fuse is to be refuse will be used and the customer may then know that he is using fuses of the proper rating for each service. Of course other and more colors may be used to further distinguish when fuses of different ratings are employed. This effect of color may be produced by applying coloring matter such as paint or the like and more particularly to the rear open end of the tubular portion 2 as at 20 (see Figure 3). The brilliance of the color effect may be further increased by extending this coating either on the inside or the outside, or both, of this tubular portion forwardly from this free end, as shown, for example, at 21 and 22. The coloring matter may, if desired, be applied to the base member 6 opposite to the end of the tubular portion 2-and it may be applied to the produced.

outer face of the sleeve 12, or to the inner face of the shell 15. The best results, however, are produced by applying the coloring matter directly to the glass top member. When viewed toward the window 4, this coloring gives the effect of tinted glass to the rim portion 5 of the top while the window 4 itself remains substantially untinted and clear so that'no effect to diminish the visibility of; the: fusible element therethrough is Thus the effect of a one piece glass top presenting a central uncolored portion and a marginal colored portion is produced without, however, requiring any actual color difference in the material of the top itself. As the coloring material may be entirely enclosed within the shell 15, it is protected thereby and cannot become erased-or rubbed off either in service or in handling and any,

preferably opaque, coloring material can be used for the purpose. The shell 15 is opaque, which also appears to aid in producing the colored effect at the desired portion 0 the top. The application of this may be readily made by merely dipping the open end of the glass top member into the coloring matter.

The fuse so treated presents a very attractive appearance when displayed for purchase, and the color when chosen to represent a distinctive capacity of fuse, has a decided value in minimizing the chances for inadvertently using fuses of the wrong capacity where the correct capacity is known.

Certain embodiments of this invention having thus been described, it should be evident to those skilled in the art that various changes and modifications might be made therein without departing from the spirit or scope of this invention as defined by the appended claims.

I claim:

1. A fuse having a one piece portion presenting a substantially colorless transparent window and a portion showing color when viewed toward said window.

2. A'fuse having a one piece colorless transparent member presenting a window, and coloring material associated with said member to give the appearance of color to a part thereof when viewed in one direction. I

3. A plug fuse having a top member of transparent material provided with a window portion and a rim about said portion, said window portion being substantially colorless and said margin presenting a color when said fuse is viewed toward said window.

4. A plug fuse comprising a one piece top having a closed end with a transparent win-, dow portion and an open end, means including a metal shell for completing the closure of said open end, and coloring material within said shell and positioned to impart the appearance of color to said closed end about said window when said closed end is viewed toward said window.

5. A transparent top for a plug fuse, which top comprises a tubular portion open at one end and closed at the other end, said closed end being provided with a clear window portion, and coloring material applied to said tubular portion back from said closed end.

6. A transparent top for a plug fuse, which top comprises a tubular portion open at one endand losed at the other end, said closed end being; provided with a clear window poiprovided with a window,

tion, and coloring material applied to the open end of said tubular portion.

7. A plug fuse comprising a one piece top of transparent material having a tubular portion closed at one end and open at the other end, said closed end having a central window portion, a base member engaging over said open end, and coloring material between said base member and said open end.

8. A plug fuse comprising a one piece top of transparent material having a tubular portion closed at one end and open at the other end, said closed end having a central window portion, a base member engaging over said open end, coloring material between said base member and said open end, and a shell of opaque material surrounding said tubular portion and said coloring material.

9. A plug fuse having a top member of transparent material having a closed end provided with a window, and having a tubular portion, a base of insulating material closing off said open end, a metal shell enclosing and fixing said top and base members together, a contact extending through said base member, a fusible element within said tubular portionconnecting said contact with said shell and having a weakened portion adjacent to said window, and coloring material enclosed by said shell in position to impart appearance of color to said top when said fuse is viewed from said window end.

10. A plug fuse having a top member of transparent material having a closed end and having a tubular portion, a base of insulating material closing ofl said open end, a metal shell enclosing and fixing said top and base members toget-her, a contact extending through said base member, a fusible element within said tubular portion connecting said contact with said shell and having a weakened portion adjacent to said window, a sleeve of non-conducting material lining said tubular portion in position to prevent sufficient contact therewhen said fusible element with of hot metal is melted to cause breakage thereof, said fusible element extending between said shell and sleeve, and coloring material enclosed by said shell in position to impart appearance of color to said top when said fuse is viewed from said window end.

In testimony whereof I have afiixed my signature.

JOSEPH G. RIESMAN. 

